CHOCOLATE is the key ingredient in a new pill being tested on patients for the first time to see if it could prevent heart attacks and stroke.

The pill will be based on cocoa flavanols, a blend of nutrients found only in the cocoa bean from which chocolate is made.

Previous smaller tests have found that the chocolate ­nutrients can improve blood pressure, cholesterol levels, the body’s use of insulin, artery health and other heart-related factors.

Chocolate has also been shown to keep wrinkles at bay by shielding skin from the harmful ageing effects of the sun.

The bad news for patients is that the flavanol capsules are coated and have no taste.

Dr JoAnn Manson, preventive medicine chief at Brigham and Women’s Hospital in Boston said: “People eat chocolate because they enjoy it, not because they think it’s good for them. The idea of the study is to see whether there are health benefits from chocolate’s ingredients minus the sugar and fat.”

She said the protective ­flavanols were not found in most sweets on the market as they are often destroyed by the processing.

The capsules will be tried out in a study of 18,000 men and women in a £12million industry-funded clinical trial by the Harvard-affiliated hospital which will be sponsored by the National Heart, Lung and Blood Institute and Mars Inc, which makes M&Ms and Snickers bars. The confectionary company has patented a way to extract the flavanols from cocoa in high concentration and put them in capsules.

But Christopher Allen, senior cardiac nurse at the British Heart Foundation, said: “Though flavanols are found in dark chocolate, this doesn’t mean we can reach for a chocolate bar and think we’re helping our hearts.

“By the time a chocolate bar lands on the supermarket shelf it will also contain added extras such as sugar and fat.”

A second part of the study will test to see if multivitamins can help prevent cancer.

Earlier research has suggested there is a benefit but it involved just older and unusually healthy men.